Light-Emitting Device and Electronic Apparatus

ABSTRACT

A light-emitting device includes a drive transistor that controls a current to be supplied to a light-emitting element from a power supply line, an element continuity portion that electrically connects the drive transistor with the light-emitting element, an initializing transistor that is turned ON to diode-connect the drive transistor, and a connecting portion that electrically connects the drive transistor with the initializing transistor. The power supply line includes a first portion extending in a predetermined direction. The element continuity portion and the connecting portion are formed from the same layer as that of the power supply line and are located on one side along the width of the first portion across the drive transistor.

CROSS-REFERENCE TO RELATED APPLICATION

This is a Divisional of application Ser. No. 12/911,344 filed Oct. 25,2010, which is a Continuation of application Ser. No. 11/548,802 filedOct. 12, 2006, which claims the benefit of Japanese Patent ApplicationNo. 2005-345299, filed in the Japanese Patent Office on Nov. 30, 2005,the entire disclosure of which is hereby incorporated by reference inits entirety.

BACKGROUND

1. Technical Field

The present invention relates to a structure of a light-emitting deviceutilizing a light-emitting material, such as an organicelectroluminescent (EL) material.

2. Related Art

As one type of active matrix light-emitting device, a structure in whicha transistor that controls a current to be supplied to a light-emittingelement (such a transistor is hereinafter referred to as a “drivetransistor”) is provided for each light-emitting element is known.Another type of active matrix-light emitting device is disclosed in U.S.Pat. No. 6,229,506 (FIG. 2) and JP-A-2004-133240 (FIGS. 2 and 3). Inthis structure, a transistor that compensates for errors of thethreshold voltage of a drive transistor (such a transistor ishereinafter referred to as an “initializing transistor”) is disposedbetween the gate electrode and the drain electrode (or source electrode)of the drive transistor. In this structure, when the initializingtransistor is turned ON to allow the drive transistor to bediode-connected, the gate electrode of the drive transistor is set to bea potential corresponding to the threshold voltage. In this state, thegate electrode of the drive transistor is changed to a potential inaccordance with a desired grayscale level. Then, a current which is notinfluenced by the threshold voltage can be supplied to the correspondinglight-emitting element.

The above-described structure requires wiring patterns for electricallyconnecting the components related to the light emission of thelight-emitting elements, for example, wiring patterns for electricallyconnecting the drive transistors and the initializing transistors(hereinafter such wiring patterns are referred to as “connectingportions”), and wiring patterns for electrically connecting the drivetransistors and the light-emitting elements (hereinafter such wiringpatterns are referred to as “element continuity portions”). However, ifsuch wiring patterns are formed in different processing steps, themanufacturing process becomes complicated and the manufacturing cost isincreased.

One solution to solving this problem is to form the connecting portionsand the element continuity portions simultaneously with the formation ofother components (for example, power supply lines) in the sameprocessing step by the patterning of one conductive film. In thismethod, however, it is necessary to form other components, such as powersupply lines, so that they can physically avoid the connecting portionsand the element continuity portions. Because of such a restriction, forexample, a sufficient width of the power supply lines cannot be ensured,and as a result, the resistance of the power supply lines cannot besufficiently reduced.

SUMMARY

An advantage of the invention is that it provides a light-emittingdevice and an electronic apparatus in which connecting portions andelement continuity portions are formed from the same layer as that ofpower supply lines while suppressing the resistance of the power supplylines.

According to an aspect of the invention, there is provided alight-emitting device including a drive transistor that controls acurrent to be supplied to a light-emitting element from a power supplyline, an element continuity portion that electrically connects the drivetransistor with the light-emitting element, an initializing transistorthat is turned ON to diode-connect the drive transistor, and aconnecting portion that electrically connects the drive transistor withthe initializing transistor. The power supply line includes a firstportion extending in a predetermined direction, and the elementcontinuity portion and the connecting portion are formed from the samelayer as that of the power supply line and are located on one side alongthe width of the first portion across the drive transistor. A specificexample of this aspect is discussed below as a first embodiment.

According to this configuration, the element continuity portion and theconnecting portion are formed from the same layer as that of the powersupply line. Thus, the manufacturing process can be simplified and themanufacturing cost can be reduced compared with the configuration inwhich the element continuity portion and the connecting portion areformed from a layer different from that of the power supply line.Additionally, since the element continuity portion and the connectingportion are disposed on one side along the width of the first portionacross the drive transistor, the space for the power supply line can beensured on the other side along the width of the first portion acrossthe drive transistor. Thus, a sufficient area (or line width) of thepower supply line can be formed so that the resistance of the powersupply line can be reduced.

Forming a plurality of components “from the same layer” is to form theplurality of components in the same step by selectively removing acommon film member (it does not matter whether the common film member isa single layer or a plurality of layers), and it does not matter whetherthe components are connected to each other or are separated from eachother.

It is preferable that the light-emitting device may further include acapacitor element electrically connected to the gate electrode of thedrive transistor. In this case, the capacitor element may be disposedopposite the connecting portion and the element continuity portionacross the drive transistor, and the first portion of the power supplyline may be overlapped with the capacitor element. With thisarrangement, since the power supply line can be formed such that it isoverlapped with the capacitor element, a more sufficient area can beensured for the power supply line.

It is preferable that the light-emitting device may further include aselection transistor that is turned ON or OFF according to a selectionsignal. In this case, the gate electrode of the drive transistor may beset to be a potential corresponding to a data signal supplied from adata line via the selection transistor that is turned ON, and theselection transistor may be disposed opposite the drive transistoracross the capacitor element. With this arrangement, a sufficient area(line width) of the power supply line can be ensured, and theconfiguration of the power supply line can be simplified (for example,without notches) compared with the configuration in which the selectiontransistor is disposed in the gap between the drive transistor and thecapacitor element.

It is preferable that a plurality of unit elements, each including thedrive transistor, the selection transistor, and the initializingtransistor, may be disposed in a direction intersecting with thepredetermined direction. In this case, the selection transistor may bedisposed on one side of the predetermined direction, and theinitializing transistor may be disposed on the other side of thepredetermined direction. With this arrangement, the selection transistorand the initializing transistor are displaced from each other in thepredetermined direction, and accordingly, the gaps among the unitelements can be decreased while maintaining electrical insulationbetween the selection transistor and the initializing transistor.

According to another aspect of the invention, there is provided alight-emitting device including a drive transistor that controls acurrent to be supplied to a light-emitting element from a power supplyline, an element continuity portion that electrically connects the drivetransistor with the light-emitting element, an initializing transistorthat is turned ON to diode-connect the drive transistor, and aconnecting portion that electrically connects the drive transistor withthe initializing transistor. The power supply line includes a firstportion extending in a predetermined direction. The element continuityportion and the connecting portion are formed from the same layer asthat of the power supply line. The element continuity portion is locatedon one side along the width of the first portion across the drivetransistor, and the connecting portion is located on the other sidealong the width of the first portion across the drive transistor. Aspecific example of this aspect is discussed below as a secondembodiment.

According to this configuration, the element continuity portion and theconnecting portion are formed from the same layer as that of the powersupply line. Thus, the manufacturing process can be simplified and themanufacturing cost can be reduced compared with the configuration inwhich the element continuity portion and the connecting portion areformed from a layer different from that of the power supply line.Additionally, since the element continuity portion and the connectingportion are respectively located on the two sides across the drivetransistor, the space for the power supply line can be ensured in thegap between the element continuity portion and the connecting portion.Thus, a sufficient area (or line width) of the power supply line can beformed so that the resistance of the power supply line can be reduced.

It is preferable that the light-emitting device may further include acapacitor element electrically connected to a gate electrode of thedrive transistor. In this case, the capacitor element may be disposed ina gap between the drive transistor and the connecting portion, and thefirst portion of the power supply line may be overlapped with thecapacitor element. With this arrangement, since the power supply linecan be formed such that it is overlapped with the capacitor element, amore sufficient area can be ensured for the power supply line.

It is also preferable that the light-emitting device may further includea selection transistor that is turned ON or OFF according to a selectionsignal. In this case, the gate electrode of the drive transistor may beset to be a potential corresponding to a data signal supplied from adata line via the selection transistor that is turned ON, and theselection transistor may be disposed opposite the drive transistoracross the capacitor element. With this arrangement, a sufficient area(line width) of the power supply line can be ensured, and theconfiguration of the power supply line can be simplified (for example,without notches) compared with the configuration in which the selectiontransistor is disposed in the gap between the drive transistor and thecapacitor element.

In the configuration in which the capacitor element is connected to thegate electrode of the drive transistor, the power supply line may beoverlapped with part of or the entire capacitor element. Typically, thecapacitor element is used for setting or holding the potential of thegate electrode of the drive transistor. For example, the capacitor maybe interposed between the gate electrode of the drive transistor and thedata line. With this configuration, due to the capacitive coupling inthe capacitor element, the gate electrode is set to be the potentialcorresponding to a change in the potential of the data line.Alternatively, the capacitor element may be interposed between the gateelectrode of the drive transistor and the wiring pattern to which aconstant potential is supplied. With this configuration, the potentialsupplied to the gate electrode of the drive transistor from the dataline can be held in the capacitor element.

It is preferable that a plurality of unit elements, each unit elementincluding the drive transistor, the element continuity portion, theinitializing transistor, and the connecting portion, may be disposed ina direction intersecting with the predetermined direction. In this case,the power supply line may include a plurality of the first portionscorresponding to the unit elements and second portions that interconnectthe first portions located adjacent to each other. With thisarrangement, the resistance of the power supply line can further bereduced compared with the configuration in which the power supply lineincludes only the first portion.

The above-described light-emitting devices can be used for various typesof electronic apparatuses. A typical example of electronic apparatusesis an apparatus utilizing the light-emitting device as a display unit.This type of electronic apparatus includes a personal computer or acellular telephone. The purpose of the light-emitting device is notrestricted to the display of images. The light-emitting device can beused for various other purposes, for example, the light-emitting devicecan be used for an exposure device (exposure head) for forming latentimages on an image carrier, such as a photosensitive drum, by theirradiation of light, a device disposed on the back side of a liquidcrystal device to illuminate the liquid crystal device (backlight), oran illumination device that is mounted on an image reader, such as ascanner, to illuminate original documents.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a block diagram illustrating a plurality of unit elementsdisposed in a light-emitting device.

FIG. 2 is a circuit diagram illustrating the electrical configuration ofeach unit element.

FIG. 3 is a plan view illustrating a unit element according to a firstembodiment of the invention.

FIG. 4 is a sectional view taken long line IV-IV of FIG. 3.

FIG. 5 is a plan view illustrating a processing step in which a gateinsulating layer is formed.

FIG. 6 is a plan view illustrating a processing step in which a firstinsulating layer is formed.

FIG. 7 is a plan view illustrating a processing step in which a secondinsulating layer is formed.

FIG. 8 is a plan view illustrating a plurality of unit elements in theprocessing step in which the first insulating layer is formed.

FIG. 9 is a plan view illustrating a plurality of unit elements in theprocessing step in which the second insulating layer is formed.

FIG. 10 is a sectional view illustrating advantages of the firstembodiment.

FIG. 11 is a circuit diagram illustrating advantages of the firstembodiment.

FIG. 12 is a plan view illustrating a unit element according to a secondembodiment of the invention.

FIG. 13 is a plan view illustrating a processing step in which a gateinsulating layer is formed.

FIG. 14 is a plan view illustrating a processing step in which a firstinsulating layer is formed.

FIG. 15 is a plan view illustrating a processing step in which a secondinsulating layer is formed.

FIG. 16 is a plan view illustrating a plurality of unit elements in theprocessing step in which the second insulating layer is formed.

FIG. 17 is a plan view illustrating a processing step in which a firstinsulating layer is formed in a modified example of the secondembodiment.

FIG. 18 is a plan view illustrating a processing step in which a secondinsulating layer is formed in a modified example of the secondembodiment.

FIG. 19 is a circuit diagram illustrating the configuration of a unitelement of a modified example.

FIG. 20 is a circuit diagram illustrating the configuration of a unitelement of another modified example.

FIG. 21 is a circuit diagram illustrating the configuration of a unitelement of another modified example.

FIG. 22 is a perspective view illustrating a personal computer, which isa specific example of an electronic apparatus according to an embodimentof the invention.

FIG. 23 is a perspective view illustrating a cellular telephone, whichis another specific example of an electronic apparatus according to anembodiment of the invention.

FIG. 24 is a perspective view illustrating a portable informationterminal, which is another specific example of an electronic apparatusaccording to an embodiment of the invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Preferred embodiments of the invention are described below withreference to the accompanying drawings.

Electrical Configuration of Light-Emitting Device

FIG. 1 is a block diagram illustrating the electrical configuration of alight-emitting device D according to preferred embodiments of theinvention. The light-emitting device D includes, as shown in FIG. 1, aplurality of selection lines 11, a plurality of initializing lines 12,and a plurality of data lines 13. The selection lines 11 and theinitializing lines 12 are extended in the x direction. The data lines 13are extended in the Y direction orthogonal to the x direction. A unitelement (pixel) P is disposed at the intersection of each pair of theselection lines 11 and initializing lines 12 and each data line 13.Accordingly, the unit elements P are disposed in a matrix in the xdirection and in the Y direction. One unit element P is the minimum unitof light emission. A high power supply potential Vdd is supplied to theunit elements P via power supply lines 15.

FIG. 2 is a circuit diagram illustrating the configuration of each unitelement P. A light-emitting element E and a drive transistor Tdr aredisposed, as shown in FIG. 2, on the path from the power supply line 15to a ground line (ground potential Gnd). The light-emitting element E isan element in which a light-emitting layer 23 composed of an organic ELmaterial is disposed between a first electrode (positive electrode) 21and a second electrode (negative electrode) 22. The first electrodes 21are formed such that the first electrode 21 of one unit element P isseparated from the first electrode 21 of the adjacent unit element P.The second electrodes 22 of the plurality of unit elements P are formedcontinuously and are grounded. The light-emitting layer 23 emits lightwith a light quantity in accordance with the current flowing from thefirst electrode 21 to the second electrode 22.

The drive transistor Tdr is a p-channel thin-film transistor that servesto control the current to be supplied to the light-emitting element E inaccordance with the potential Vg of the gate electrode (hereinaftersimply referred to as the “gate potential”). The source electrode (S) ofthe drive transistor Tdr is connected to the power supply line 15, whilethe drain electrode (D) thereof is connected to the first electrode 21of the light-emitting element E.

An n-channel transistor (hereinafter referred to as the “initializingtransistor”) Tint that controls electrical connection between the gateelectrode and the drain electrode (first electrode 21 of thelight-emitting element E) of the drive transistor Tdr is disposedbetween the gate electrode and the drain electrode of the drivetransistor Tdr. The gate electrode of the initializing transistor Tintis connected to the initializing line 12. An initializing signal Sb issupplied to the initializing line 12 from a drive circuit (not shown).When the initializing signal Sb reaches an active level to allow theinitializing transistor Tint to be turned ON, the gate electrode and thedrain electrode of the drive transistor Tdr are electrically connected(diode-connected) to each other.

The unit element P includes, as shown in FIG. 2, a capacitor element C1formed of an electrode E1 and an electrode E2. The electrode E1 isconnected to the gate electrode of the drive transistor Tdr. Ann-channel transistor (hereinafter referred to as the “selectiontransistor”) Tsl for controlling electrical connection between theelectrode E2 and the data line 13 is disposed therebetween. The gateelectrode of the selection transistor Tsl is connected to the selectionline 11. A selection signal Sa is supplied to the selection line 11 froma drive circuit (not shown). The conductivity types of the drivetransistor Tdr, the selection transistor Tsl, and the initializingtransistor Tint can be changed from those shown in FIG. 2 if necessary.

The operation of one unit element P is described below by individuallyconsidering the operation in each of the initializing period, thewriting period, and the driving period. In the initializing period, apredetermined potential Vref is supplied to the data line 13 from adrive circuit (not shown), and also, the selection signal Sa of theselection line 11 and the initializing signal Sb of the initializingline 12 are maintained at the active level (high level). Accordingly,the potential Vref is supplied to the electrode E2 of the capacitorelement C1 from the data line 13 via the selection transistor Tsl. Then,the initializing transistor Tint is turned ON to allow the drivetransistor Tdr to be diode-connected. Accordingly, the gate potential Vgof the drive transistor Tdr converges into the difference (Vg=Vdd−Vth)between the power supply potential Vdd supplied to the power supply line15 and the threshold voltage Vth of the drive transistor Tdr.

Then, in the writing period after the lapse of the initializing period,the initializing signal Sb is shifted to the non-active level (lowlevel). Accordingly, the initializing transistor Tint is turned OFF toallow the diode-connection of the drive transistor Tdr to be canceled.The potential Vref supplied to the electrode E2 from the data line 13 ischanged to the potential Vdata while the selection transistor Tslremains ON. The potential Vdata is a potential corresponding to thegrayscale level specified by the unit element P.

The impedance of the gate electrode of the drive transistor Tdr issufficiently high. Accordingly, if the potential of the electrode E2 ischanged from the potential Vref to the data potential Vdata by ΔV(=Vref−Vdata), the potential of the electrode E1 is also changed fromthe potential Vg(=Vdd−Vth) set in the initializing period due tocapacitive coupling in the capacitor element C1. In this case, a changein the potential of the electrode E1 is determined by the ratio of thecapacitance of the capacitor element C1 to other parasitic capacitances,for example, the gate capacitance of the drive transistor Tdr andparasitic capacitances of other wiring patterns. More specifically, whenthe capacitance of the capacitor element C1 is represented by C and whenthe parasitic capacitances are indicated by Cs, a change in thepotential of the electrode E1 can be indicated by ΔV·C/(C+Cs).Accordingly, the gate potential Vg of the drive transistor Tdr ischanged to the level expressed by equation (1) at the end of the writingperiod:

Vg=Vdd−Vth−k·ΔV  (1)

where k=C/(C+Cs).

In the driving period after the lapse of the writing period, theselection signal Sa is shifted to the non-active level to allow theselection transistor Tsl to be turned OFF. Then, the currentcorresponding to the gate potential Vg of the drive transistor Tdr issupplied to the light-emitting element E from the power supply line 15through the source electrode and the drain electrode of the drivetransistor Tdr. The light-emitting element E then emits light with thelight quantity corresponding to the data potential Vdata.

The current I supplied to the light-emitting element E in the drivingperiod can be expressed by equation (2), assuming that the drivetransistor Tdr is operated in a saturation region:

$\begin{matrix}\begin{matrix}{I = {\left( {\beta \text{/}2} \right)\left( {{Vgs} - {Vth}} \right)2}} \\{= {\left( {\beta \text{/}2} \right)\left( {{Vdd} - {Vg} - {Vth}} \right)2}}\end{matrix} & (2)\end{matrix}$

where β designates the gain coefficient of the drive transistor Tdr, andVgs indicates the gate-source voltage of the drive transistor Tdr.

Equation (2) can be modified as follows by substituting equation (1)into equation (2).

I=(β/2)(k·ΔV)2

That is, the current I supplied to the light-emitting element E is notinfluenced by the threshold voltage Vth of the drive transistor Tdr. Itis thus possible to suppress errors of the light quantities(non-uniformities of the luminance) of the light-emitting elements Ecaused by variations of the threshold voltages Vth of the drivetransistors Tdr. Such variations are originated from the deviations ofthe threshold voltage Vth from the design value or the difference in thedrive transistors Tdr of the unit elements P.

Specific Structure of Unit Element P

The specific structure of the above-described unit elements P isdescribed below with reference to the accompanying drawings. For thesake of convenience of description, the dimensions and ratios of thecomponents shown in the drawings are changed from those of the actualdevices if necessary.

First Embodiment

A description is given below of the specific structure of the unitelements P of the light-emitting device D according to a firstembodiment of the invention. FIG. 3 is a plan view illustrating one unitelement P, and FIG. 4 is a sectional view taken along line IV-IV of FIG.3. Although FIG. 3 is a plan view, for easy understanding, thecomponents shown in FIG. 3 corresponding to the counterparts in FIG. 4are hatched in a manner similar to the counterparts in FIG. 4. The sameapplies to the other plan views.

The components, such as the drive transistor Tdr and the light-emittingelement E, of the unit element P shown in FIG. 2 are formed, as shown inFIG. 4, on the surface of a substrate 10. The substrate 10 is a planarmember composed of an insulating material, such as glass or plastic.When forming the components of the unit element P on the surface of thesubstrate 10, an insulating film, such as a silicon oxide or siliconnitride film, covering the substrate 10 may be used as an underlayer ofthe components. Since the light-emitting device D of the firstembodiment is a top emission type, it is not always necessary that thesubstrate 10 exhibit a light transmittance characteristic.

FIGS. 5 through 7 are plan views illustrating the surface of thesubstrate 10 when the unit element P is formed on the substrate 10 invarious processing steps. In FIGS. 5 through 7, a region A in which thefirst electrode 21 shown in FIG. 3 is to be formed is indicated by thetwo-dot-chain lines.

A semiconductor layer 31 and a semiconductor layer 41 are formed, asshown in FIGS. 4 and 5, on the surface of the substrate 10 by asemiconductor material, such as silicon. The semiconductor layer 31 andthe semiconductor layer 41 are simultaneously formed in the same step bythe patterning of a film member that is continuously formed on theentire area of the substrate 10. As in the relationship between thesemiconductor layer 31 and the semiconductor layer 41, forming aplurality of components in the same step by selectively removing acommon film member (it does not matter whether the common film member isa single layer or a plurality of layers) is referred to as “formingcomponents from the same layer”. The components formed from the samelayer are composed of the same material, and have substantially the samethickness. With this configuration, the manufacturing process can besimplified and the manufacturing cost can be reduced, compared with thecase where components are formed from different layers.

The semiconductor layer 31 includes, as shown in FIGS. 4 and 5, a firstelement portion 311 and a second element portion 312. The first elementportion 311, which is formed substantially in a rectangular shape,serves as the semiconductor layer of the drive transistor Tdr. Thesecond element portion 312 serves as the semiconductor layer of theinitializing transistor Tint. The second element portion 312 is formedtoward the positive side in the x direction and toward the negative sidein the Y direction (i.e., at the top right of the first element portion311) when viewed from the first element portion 311. More specifically,as shown in FIG. 5, the second element portion 312 includes a part 312 aextending toward the negative side in the Y direction from the firstelement portion 311, a part 312 b extending toward the positive side inthe x direction from the part 312 a, and a part 312 c extending towardthe positive side in the Y direction from the part 312 b.

The semiconductor layer 41, which is disposed toward the positive sidein the Y direction when viewed from the semiconductor layer 31, includesthe electrode E2, which is formed substantially in a rectangular shapeand forms the capacitor element C1 shown in FIG. 2, and an elementportion 411 extending in the Y direction from the electrode E2. Theelement portion 411 serves as the semiconductor layer of the selectiontransistor Tsl, and is formed toward the negative side in the xdirection and toward the positive side in the Y direction (i.e., at thebottom left of the electrode E2) when viewed from the electrode E2.

As shown in FIG. 4, the entire surface of the substrate 10 on which thesemiconductor layer 31 and the semiconductor layer 41 are formed iscovered with a gate insulating layer L0. On the surface of the gateinsulating layer L0, as shown in FIGS. 4 and 6, the selection line 11,the initializing line 12, an intermediate conductor 51, and a first dataline portion 131 are formed from the same layer.

The selection line 11 is extended in the x direction over the pluralityof unit elements P and is overlapped with the element portion 411 of thesemiconductor layer 41. The area of the element portion 411 that isoverlapped with the selection line 11 across the gate insulating layerL0 serves as the channel region of the selection transistor Tsl. Theinitializing line 12 is extended in the x direction over the pluralityof unit elements P and is overlapped with the second element portion 312of the semiconductor layer 31. The area of the part 312 a or the area ofthe part 312 c that is overlapped with the initializing line 12 acrossthe gate insulating layer L0 serves as the channel region of theinitializing transistor Tint. Accordingly, the initializing transistorTint in this embodiment is a dual-gate-structured transistor.

The intermediate conductor 51 is formed in the gap between the selectionline 11 and the initializing line 12, and includes the electrode E1, agate electrode 511, and an interconnecting portion 513. The electrode E1is formed substantially in a rectangular shape and is overlapped withthe electrode E2 of the semiconductor layer 41 when viewedperpendicularly to the substrate 10. The electrode E1 and the electrodeE2 face each other across the gate insulating layer L0 (dielectric), asshown in FIGS. 4 and 6 so that they form the capacitor element C1 shownin FIG. 2.

The interconnecting portion 513 is extended toward the negative side inthe Y direction from the top right of the electrode E1. The gateelectrode 511 is extended toward the negative side in the x directionfrom the interconnecting portion 513 such that it faces the electrode E1with a gap therebetween, and is overlapped with the first elementportion 311 over the entire width (X direction) thereof. As shown inFIG. 4, the area of the first element portion 311 that faces the gateelectrode 511 across the insulating layer L0 serves as a channel region311 c of the drive transistor Tdr. The area of the first element portion311 that is located closer to the electrode E2 than the channel region311 c (i.e., the area located in the gap between the gate electrode 511and the electrode E1, as shown in FIG. 6, when viewed perpendicularly tothe substrate 10) is a source region 311 s, and the area of the firstelement portion 311 that is located opposite the source region 311 s isa drain region 311 d.

The first data line portion 131 forms the data line 13 shown in FIG. 2.The first data line portion 131 is disposed toward the negative side inthe x direction when viewed from the intermediate conductor 51 and isextended in the Y direction in the gap between the selection line 11 andthe initializing line 12.

FIG. 8 is a plan view illustrating four unit elements P that are in theprocessing step shown in FIG. 6 and are disposed in the x direction andin the Y direction. In each unit element P, as shown in FIGS. 6 and 8,the second element portion 312 (initializing transistor Tint) formed atthe periphery of the negative side in the Y direction is located towardthe positive side in the x direction, while the element portion 411(selection transistor Tsl) formed at the periphery of the negative sidein the Y direction is located toward the negative side in the xdirection.

It is now assumed that the second element portion 312 and the elementportion 411 are disposed toward the same side in the x direction in eachunit element P. With this configuration, it is necessary to ensure asufficient gap (indicated by region B in FIG. 8) between unit elements Padjacent to each other in the Y direction so that the second elementportion 312 and the element portion 411 can be separated from eachother. With this configuration, the high definition of the unit elementsP is impaired. According to this embodiment, however, the second elementportion 312 and the element portion 411 are displaced from each other inthe x direction, and thus, the second element portion 312 and theelement portion 411 are alternately disposed in the x direction in theregion B. With this configuration, even if the width of the region B isdecreased, the second element portion 312 and the element portion 411can be separated from each other, and the high definition of the unitelements P can be implemented.

The entire surface of the gate insulating layer L0 on which theintermediate conductor 51 and the first data line portion 131 are formedis, as shown in FIG. 4, covered with a first insulating layer L1. On thesurface of the first insulating layer L1, as shown in FIGS. 4 and 7, aconnecting portion 61, an element continuity portion 71, the powersupply line 15, and a second data line portion 132 are formed from thesame layer composed of a conductive material.

When viewed perpendicularly to the substrate 10, as shown in FIG. 7, theconnecting portion 61 is overlapped with the end of the part 312 c ofthe second element portion 312 located at the positive side in the Ydirection and also overlapped with the intermediate conductor 51 (gateelectrode 511). The connecting portion 61 is electrically connected tothe part 312 c through a contact hole Ha1 passing through the firstinsulating layer L1 and the gate insulating layer L0, and is alsoelectrically connected to the intermediate conductor 51 through acontact hole Ha2 passing the first insulating layer L1. That is, thegate electrode 511 (electrode E1 of the capacitor element C1) of thedrive transistor Tdr and the initializing transistor Tint areelectrically connected to each other through the connecting portion 61.In this specification, contact holes are used for electricallyconnecting the components disposed on one side of an insulating layerwith the components disposed on the other side of the insulating layer,and more specifically, the contact holes are, for example, holes passingthrough the insulating layer along the thickness thereof. The planarconfiguration of the contact holes can be determined as desired.

The element continuity portion 71 is disposed between the drivetransistor Tdr and the light-emitting element E to electrically connectthem. When viewed perpendicularly to the substrate 10, the elementcontinuity portion 71 is located opposite the capacitor element C1across the drive transistor Tdr (i.e., in the region toward the negativeside in the Y direction with respect to the drive transistor Tdr). Inthis embodiment, the element continuity portion 71 is configured suchthat, when viewed perpendicularly to the substrate 10, a part 711 thatis overlapped with the drain region 311 d of the first element portion311 is continuously formed with a part 712 located opposite the part 711across the initializing portion 12.

In the area of the first insulating layer L1 that is overlapped with thedrain region 311 d, when viewed perpendicularly to the substrate 10, aplurality of contact holes Ha3 passing through the first insulatinglayer L1 and the gate insulating layer L0 are formed. The contact holesHa3 are disposed in the x direction in which the gate electrode 511 isextended (i.e., in the direction along the channel width of the drivetransistor Tdr). The part 711 of the element continuity portion 71 iselectrically connected to the drain region 311 d of the drive transistorTdr through the contact holes Ha3.

FIG. 9 is a plan view illustrating the four unit elements P that are inthe processing step shown in FIG. 8 and are disposed in the x directionand in the Y direction. The power supply lines 15 are bar-like wiringpatterns, as shown in FIGS. 7 and 9, which extend in the x direction inwhich the plurality of unit elements P are disposed. The power supplyline 15 is overlapped with the capacitor element C1 of each unit elementP and the source region 311 s of the drive transistor Tdr, when viewedperpendicularly to the substrate 10. In the area of the first insulatinglayer L1 that is overlapped with the source region 311 s, a plurality ofcontact holes Ha4 passing through the first insulating layer L1 and thegate insulating layer L0 are formed, as shown in FIG. 7. The contactholes Ha4 are located in the x direction in which the gate electrode 511is extended. The power supply line 15 is electrically connected to thesource region 311 s of the drive transistor Tdr through the contactholes Ha4.

In this embodiment, the configuration and dimensions of the power supplylines 15 are determined so that the power supply lines 15 are notoverlapped with the selection transistors Tsl (element portions 411),the selection lines 11, the initializing transistors Tint (secondelement portion 312), and the initializing lines 12, when viewedperpendicularly to the substrate 10. In other words, the power supplylines 15 are extended in the x direction, as shown in FIG. 9, in the gapbetween the selection transistors Tsl disposed along the selection lines11 and the initializing transistors Tint disposed along the initializinglines 12.

The second data line portion 132 forms, together with the first dataline portion 131, the data line 13, and is extended in the Y directionin the gap between adjacent power supply lines 15, as shown in FIGS. 7and 9. An end 132 a of the second data line portion 132 located at thepositive (lower) side in the Y direction is overlapped with, as shown inFIG. 7, an end 131 a (see FIG. 6) of the first data line portion 131located at the negative (upper) side in the Y direction. The end 132 aand the end 131 a are electrically connected to each other through thecontact hole Ha5 passing through the first insulating layer L1.Similarly, an end 132 b of the second data line portion 132 located atthe negative side in the Y direction is overlapped with, as shown inFIG. 7, an end 131 b (see FIG. 6) of the first data line portion 131located at the positive side in the Y direction through a contact holeHa6. In this manner, the first data line portions 131 and the seconddata line portions 132 which are alternately disposed in the Y directionare electrically connected to each other so that the data lines 13linearly extending in the Y direction can be formed.

A branched portion 134 is continuously provided, as shown in FIG. 7,from the second data line portion 132. The branched portion 134 islocated opposite the capacitor element C1 across the selection line 11,and is extended in the x direction to be overlapped with the elementportion 411 of the semiconductor layer 41. The branched portion 134 iselectrically connected to the element portion 411 through a contact holeHa1 passing through the first insulating layer L1 and the gateinsulating layer L0. That is, the selection transistor Tsl and the dataline 13 are electrically connected to each other through the branchedportion 134.

The capacitor element C1 of each unit element P is, as shown in FIGS. 7and 9, located adjacent to the data line 13 of the right-adjacent unitelement P located at the positive side in the x direction. FIG. 10 is anenlarged, sectional view illustrating one unit element P1 and theright-adjacent unit element P2 located at the positive side in the xdirection. In FIG. 10, the intermediate conductor 51 (in particular, theelectrode E1 of the capacitor element C1) of the unit element P1 and thefirst data line portion 131 of the data line 13 corresponding to theunit element P2 are shown.

The intermediate conductor 51 and the first data line portion 131 areformed from the same layer and are thus located adjacent to each other.Accordingly, a capacitor (parasitic capacitor) Ca is formed due tocapacitive coupling between the intermediate conductor 51 and the firstdata line portion 131. Thus, although the potential Vg of the electrodeE1 (and the gate electrode 511 of the drive transistor Tdr) of the unitelement P1 is set intrinsically only by a change in the potential of thedata line 13 corresponding to the unit element P1 (i.e., the voltagecorresponding to the grayscale level of the unit element P1), it is alsoinfluenced by a change in the potential of the first data line portion131 corresponding to the unit element P2 (i.e., the voltagecorresponding to the grayscale level of the unit element P2). That is,it is difficult to precisely set the gate potential Vg of the drivetransistor Tdr of each unit element P, and errors may occur in the lightquantities of the light-emitting elements E.

The first data line portion 131 and the power supply line 15 face eachother across the first insulating layer L1, as shown in FIG. 10, so thata capacitance is formed therebetween. In this embodiment, as shown inFIG. 10, the capacitance c2 of the capacitor Cb formed between the firstdata line portion 131 of the unit element P2 and the power supply line15 is larger than the capacitance c1 of the capacitor Ca formed betweenthe first data line portion 131 and the intermediate conductor 51(electrode E1) of the unit element P1. With this configuration, theinfluence on the intermediate conductor 51 (electrode E1) of the unitelement P1 caused by a change in the potential of the first data lineportion 131 of the unit element P2 is alleviated by the capacitor Cb.Accordingly, the gate potential Vg of the drive transistor Tdr of eachunit element P and the light quantity of the light-emitting element Ecorresponding to the gate potential Vg can be set to desired values withhigh precision.

In this embodiment, the distance (thickness of the first insulting layerL1) between the first data line portion 131 and the power supply line 15and the space between the intermediate conductor 51 of the unit elementP1 and the first data line portion 131 of the unit element P2 aredetermined so that the above-described condition (c2>c1) is satisfied.More specifically, the distance (thickness of the first insulting layerL1) between the first data line portion 131 of the unit element P2 andthe power supply line 15 is smaller than the space between theintermediate conductor 51 of the unit element P1 and the first data lineportion 131 of the unit element P2. Additionally, the area by which thefirst data line portion 131 of the unit element P2 faces the powersupply line 15 through the first insulating layer L1 (i.e., the area ofthe first data line portion 131 that is overlapped with the power supplyline 15 when viewed perpendicularly to the substrate 10) is larger thanthe area by which the first data line portion 131 faces the intermediateconductor 151 of the unit element P1 (i.e., the area by which the sidesurface of the intermediate conductor 51, when viewed perpendicularly tothe substrate 10, faces the side surface of the first data line portion131). By selecting the dimensions of the components and spaces betweenthe components as described above, the capacitance c2 can be set to belarger than the capacitance c1.

To precisely set the gate potential Vg of the drive transistor Tdr inaccordance with the data potential Vdata of the data line 13, it isdesirable that the capacitance c2 of the capacitor Cb of the unitelement P2 is smaller than the capacitance C of the capacitor element C1of the unit element P2 (synthesized capacitance of the capacitor elementC1 and parasitic capacitance Cs if the parasitic capacitor Cs is formedin the gate electrode 511). To satisfy this condition, the gap betweenthe first data line portion 131 and the power supply line 15 is set tobe larger than the gap between the electrode E1 and the electrode E2 ofthe capacitor element C1. More specifically, the thickness of the firstinsulating layer L1 intervening between the first data line portion 131and the power supply line 15 (i.e., the thickness of the dielectricmember of the capacitor Cb) is set to be larger than the thickness ofthe gate insulating layer L0 intervening between the electrode E1 andthe electrode E2 (i.e., the thickness of the dielectric member of thecapacitor element C1). Additionally, the area by which the electrode E1and the electrode E2 face each other (i.e., the area of the capacitorelement C1) is set to be larger than the area by which the first dataline portion 131 and the power supply line 15 face each other. With thisarrangement, the capacitance c2 of the capacitor Cb becomes smaller thanthe capacitance C of the capacitor element C1.

As shown in FIG. 4, the entire surface of the first insulating layer L1on which the second data line portion 132 and the power supply line 15are formed is covered with a second insulating layer L2. The firstelectrode 21 is formed, as shown in FIGS. 3 and 4, on the surface of thesecond insulating layer L2. The first electrode 21 is formedsubstantially in a rectangular shape and is overlapped with the elementcontinuity portion 71, the drive transistor Tdr, and the capacitorelement C1, when viewed perpendicularly to the substrate 10. In thisembodiment, the first electrode 21 is formed of a light-reflective,conductive material, such as a metal, for example, aluminum or silver,or an alloy essentially consisting of such a metal. The first electrode21 is electrically connected to the part 712 of the element continuityportion 71 through a contact hole Ha8 passing through the secondinsulating layer L2. That is, the drain region 311 d of the drivetransistor Tdr is electrically connected to the first electrode 21 ofthe light-emitting element E through the element continuity portion 71.

Barriers 25 that partition the boundaries of the unit elements P areformed in a lattice-like shape on the surface of the second insulatinglayer L2 on which the first electrodes 21 are formed. The barriers 25have the function of electrically insulating the first electrodes 21located adjacent to each other, i.e., the function of controlling thepotentials of the individual first electrodes 21. The light-emittinglayer 23 of each light-emitting element E is enclosed in the innerperiphery of the barrier 25 and is formed in a recess having the firstelectrode 21 as the bottom surface. Various functional layers (holeinjection layer, hole transport layer, electron injection layer,electron transport layer, hole block layer, and electron block layer)for promoting or making efficient the light emission of thelight-emitting layer 23 may be laminated on the light-emitting layer 23.

The second electrode 22 are formed continuously over the plurality ofunit elements P, and covers the light-emitting layer 23 and the barrier25. Accordingly, the barrier 25 serves the function of electricallyinsulating the first electrode 21 from the second electrode 22 in thegap of each light-emitting element E. In other words, the barrier 25defines the area in which the current flows between the first electrode21 and the second electrode 22 (i.e., the light-emitting area). Thesecond electrode 22 is formed of a light-transmissive, conductivematerial, such as indium tin oxide (ITO) or indium zinc oxide (IZO).Accordingly, light emitted from the light-emitting layer 23 toward theside opposite the substrate 10 and light emitted from the light-emittinglayer 23 toward the substrate 10 and reflected on the surface of thefirst electrode 21 pass through the second electrode 22 and are output.That is, the light-emitting device D of this embodiment is a topemission type.

The entire surface of the second electrode 22 is covered with a sealingmaterial (not shown). The sealing material includes a first layer thatprotects the second electrode 22, a second layer that flattens thedifference in the level of the surface of the second electrode 22, athird layer (barrier layer) that prevents the entry of impurities (forexample, water) into the second electrode 22 and the light-emittinglayer 23, the first layer, the second layer, and the third layer beinglaminated from the second electrode 22 in that order.

As described above, in this embodiment, the element continuity portion71 is located opposite the capacitor element C1 across the drivetransistor Tdr. With this configuration, the effect of reducing thecapacitance required for the capacitor element C1 can be achieved. Thiseffect is described below more specifically.

It is now assumed that the element continuity portion 71 is disposed inthe gap between the drive transistor Tdr and the capacitor element C1when viewed perpendicularly to the substrate 10 (such a configuration isreferred to as “configuration 1”). In the configuration 1, the electrodeE1 of the capacitor element C1 and the element continuity portion 71 arelocated in proximity with each other across the first insulating layerL1. Accordingly, a capacitance Cx is formed between the electrode E1 andthe element continuity portion 71 (first electrode 21), as indicated bythe broken lines in FIG. 11.

During the writing period, the potential of the electrode E1 is changedby ΔV·C/(C+Cs). In the configuration 1, the capacitance Cs is increasedby the capacitance Cx compared with the case where the electrode E1 andthe element continuity portion 71 are not capacitively coupled to eachother. Accordingly, the fluctuations of the gate potential Vg of thedrive transistor Tdr in response to the change ΔV in the potential ofthe data line 13 are restricted. Thus, in order to fluctuate the gatepotential Vg in a wide range in response to the change ΔV in thepotential of the data line 13 (i.e., to ensure a sufficient range of thelight quantities of the light-emitting element E), it is necessary toensure a sufficient capacitance C of the capacitor element C1 byreducing the thickness of the gate insulating layer L0 or increasing theareas of the electrode E1 and the electrode E2. Since there arelimitations on reducing the thickness of the gate insulating layer L0,it is necessary to increase the areas of the electrode E1 and theelectrode E2. On the other hand, however, an increase in the area of thecapacitor element C1 impairs the high definition of the unit elements P.

If the electrode E1 and the element continuity portion 71 are separatedfrom each other by forming the first insulating layer L1 to besufficiently thick, the capacitance Cx can be reduced in theconfiguration 1. However, if the first insulating layer L1 is formed tobe thick, defects related to film formation, such as cracks, are likelyto occur, and also, the perfect electrical continuity among thecomponents cannot be established due to the defects of contact holes(for example, contact holes cannot be perfectly formed from the firstinsulating layer L1). Thus, there are also limitations on reducing thecapacitance Cx by this method.

In contrast, according to this embodiment, since the element continuityportion 71 is disposed opposite the capacitor element C1 across thedrive transistor Tdr, the capacitance Cx generated between the electrodeE1 and the element continuity portion 71 can be reduced to a sufficientlevel compared with the configuration 1. Accordingly, the gate potentialVg of the gate electrode 511 of the drive transistor Tdr (and the lightquantity of the light-emitting element E) can be changed in a wide rangewithout the need to considerably increase the area of the capacitorelement E1 as in the configuration 1.

In this embodiment, both the element continuity portion 71 and theconnecting portion 61 formed from the same layer as that of the powersupply line 15 are located farther toward the negative side in the Ydirection than the drive transistor Tdr (i.e., on one side along thewidth of the power supply line 15) when viewed perpendicularly to thesubstrate 10. With this configuration, a sufficient space can be ensuredfor the power supply line 15 on the surface of the first insulatinglayer L1 farther toward the positive side in the Y direction than drivetransistor Tdr (i.e., on the other side along the width of the powersupply line 15). Accordingly, the power supply line 15 can be formed tobe wide so that the resistance can be sufficiently reduced. Inparticular, in this embodiment, since the power supply line 15 can beformed such that it is overlapped with the capacitor element C1, theresistance of the power supply line 15 can be reduced more considerablycompared with the configuration in which the power supply line 15 isoverlapped with only the source region 31 s of the drive transistor Tdr.The reduced resistance of the power supply line 15 suppresses a voltagedrop in the power supply line 15. As a result, variations in the powersupply potential Vdd supplied to the unit elements P and variations inthe light quantities of the light-emitting elements E can be reduced.

In the configuration in which the element continuity portion 71 and theconnecting portion 61 are disposed in the gap between the drivetransistor Tdr and the capacitor element C1, it is necessary to form thepower supply line 15 such that it can physically avoid the elementcontinuity portion 71 and the connecting portion 61. However, thecomplexity of the configuration of the power supply line 15 encourages abreak or damage in the power supply line 15 because of the manufacturingtechnique. Conversely, according to this embodiment, since a space canbe ensured for the power supply line 15 opposite the element continuityportion 71 and the connecting portion 61 across the drive transistorTdr, the power supply line 15 can be formed in a simple bar-like shape,as shown in FIG. 7. As a result, a break or damage in the power supplyline 15 can be suppressed so that the yield of the light-emittingdevices D can be improved.

With a view to reducing the resistance of the power supply line 15, thepower supply line 15 could be overlapped with, not only the drivetransistor Tdr and the capacitor element C1, but also the selectiontransistor Tsl and the initializing transistor Tint. Such aconfiguration is hereinafter referred to as “configuration 2”. In theconfiguration 2, however, the selection transistor Tsl or the selectionline 11 is capacitively coupled to the power supply line 15 (i.e., aparasitic capacitance is generated therebetween), which encourages theoccurrence of blunt waves in the selection signal Sa. Similarly, thecapacitance generated between the initializing transistor Tint or theinitializing line 12 and the power supply line 15 may cause blunt wavesin the initializing signal Sb. Thus, in the configuration 2, theswitching of the selection transistor Tsl or the initializing transistorTint may be delayed.

On the other hand, according to this embodiment, when viewedperpendicularly to the substrate 10, the power supply line 15 is notoverlapped with the selection transistor Tsl or the selection line 11 orthe initializing transistor Tint or the initializing line 12.Accordingly, the capacitance between the power supply line 15 and theselection transistor Tsl or the selection line 11 or the initializingtransistor Tint or the initializing line is smaller than that of theconfiguration 2. Thus, the occurrence of blunt waves in the selectionsignal Sa or the initializing signal Sb can be suppressed so that thefast operation of the selection transistor Tsl or the initializingtransistor Tint can be achieved.

Second Embodiment

The specific configuration of a unit element P according to a secondembodiment of the invention is described below. FIG. 12 is a plan viewillustrating the configuration of the unit element P of the secondembodiment. FIGS. 13 through 15 are plan views illustrating the surfaceof the substrate 10 when the unit element P is formed on the substrate10 in various processing steps. In the following description, the samecomponents as those of the first embodiment are designated with likereference numerals, and an explanation thereof is thus omitted.

On the surface of the substrate 10, as shown in FIG. 13, a semiconductorlayer 32, a semiconductor layer 42, and a semiconductor layer 45 areformed from the same layer by using a semiconductor material. Thesemiconductor layer 32, which is formed substantially in a rectangularshape, forms the drive transistor Tdr. The semiconductor layer 42 isformed toward the positive side in the Y direction when viewed from thesemiconductor layer 32, and includes a substantially rectangularelectrode E2 and an element portion 421 extending in the x directionfrom the bottom left portion of the electrode E2. The element portion421 functions as the semiconductor layer of the selection transistorTsl. The semiconductor layer 45 forms the initializing transistor Tintand is extended in the x direction while facing the semiconductor layer32 across the semiconductor layer 42.

The surface of the substrate 10 on which the above-described componentsare formed is covered with the gate insulating layer L0. As shown inFIG. 14, the first data line portion 131, the selection line 11, theinitializing line 12, the intermediate conductor 52, and a first relaywiring pattern 171 are formed from the same layer on the surface of thegate insulating layer L0. As in the first embodiment, the first dataline portion 131 forms the data line 13, and is extended in the Ydirection and is located farther toward the positive side in the xdirection than the intermediate conductor 52.

The initializing line 12 includes a first gate electrode 121 and asecond gate electrode 122 which are branched from the midpoint portionof the initializing line 12 toward the negative side of the Y directionand which are overlapped with the semiconductor layer 45. The areas ofthe semiconductor layer 45 that are overlapped with the first gateelectrode 121 and the second gate electrode 122 serve as the channelregion of the initializing transistor Tint. Similarly, the selectionline 11 includes a first gate electrode 111 and a second gate electrode112 which are branched from the midpoint portion of the selection line11 toward the negative side in the Y direction and which are overlappedwith the element portion 421 of the semiconductor layer 42. The firstgate electrode 111 and the second gate electrode 112 are locatedadjacent to each other in the x direction with a gap therebetween. Theareas of the element portion 421 that are overlapped with the first gateelectrode 111 and the second gate electrode 112 across the gateinsulating layer L0 serve as the channel region of the selectiontransistor Tsl. Accordingly, the selection transistor Tsl and theinitializing transistor Tint are dual-gate-structured thin-filmtransistors.

The intermediate conductor 52 includes an electrode E1 that forms thecapacitor element C1 while facing an electrode E2, a gate electrode 521extending from the electrode E1 toward the negative side in the Ydirection, and a connecting portion 523 projecting from substantiallythe central portion of the electrode E1 toward the positive side in theY direction. The gate electrode 521 is extended in the Y direction suchthat it is overlapped with the entire width of the semiconductor layer32 in the Y direction. As shown in FIG. 14, the area of thesemiconductor layer 32 that faces the gate electrode 521 across the gateinsulating layer L0 serves as a channel region 32 c of the drivetransistor Tdr. A drain region 32 d and a source region 32 s arerespectively disposed toward the negative side and the positive side inthe x direction across the channel region 32 c.

The first relay wiring pattern 171 is a wiring pattern for electricallyconnecting the initializing transistor Tint with the drain region 32 dof the drive transistor Tdr (such a wiring pattern is hereinafterreferred to as a “relay wiring pattern”), and is extended in the Ydirection and is located farther toward the negative side in the xdirection than the intermediate conductor 52. That is, in thisembodiment, the intermediate conductor 52 is disposed in the gap betweenthe first data line portion 131 and the first relay wiring pattern 171.

The surface of the gate insulating layer L0 on which the above-describedcomponents are formed is covered with the first insulating layer L1. Asshown in FIGS. 12 and 15, the second data line portion 132, a connectingportion 62, a second relay wiring pattern 172, an element continuityportion 72, and the power supply line 15 are formed on the surface ofthe first insulating layer L1.

As in the first embodiment, the second data line portion 132 forms,together with the first data line portion 131, the data line 13. Thesecond data line portion 132 is extended in the Y direction from the end132 a which is electrically connected to the top end 131 a (see FIG. 14)of the first data line portion 131 through a contact hole Hb1 to the end132 b. The end 132 b is electrically connected to the bottom end 131 b(see FIG. 14) of the first data line portion 131 through a contact holeHb2. The second data line portion 132 is electrically connected to theend of the element portion 421 through a contact hole Hb3 passingthrough the first insulating layer L1 and the gate insulating layer L0.That is, the data line 13 and the selection transistor Tsl areelectrically connected to each other through the contact hole Hb3.

The connecting portion 62 is extended, as shown in FIGS. 14 and 15, inthe Y direction such that it is overlapped with the connecting portion523 of the intermediate conductor 52 and an end 451 of the semiconductorlayer 45 located at the positive side in the x direction. The connectingportion 62 is electrically connected to the connecting portion 523(electrode E1 and gate electrode 521) through a contact hole Hb4 passingthrough the first insulating layer L1, and is also connected to the end451 of the semiconductor layer 45 through a contact hole Hb5 passingthrough the first insulating layer L1 and the gate insulating layer L0.That is, the electrode E1 of the capacitor element C1 (and the gateelectrode 521 of the drive transistor Tdr) and the initializingtransistor Tint are electrically connected to each other through theconnecting portion 62.

When viewed perpendicularly to the substrate 10, as shown in FIG. 15,the connecting portion 62 is located in the gap between the first gateelectrode 111 and the second gate electrode 112 of the selectiontransistor Tsl. Accordingly, the connecting portion 62 is not overlappedwith the first gate electrode 111 or the second gate electrode 112. Ifthe connecting portion 62 is overlapped with the first gate electrode111 (or the second gate electrode 112), capacitive coupled isestablished therebetween. Accordingly, due to a change in the potentialof the connecting portion 62 (i.e., the potential of the electrode E1and the potential of the gate electrode 511 of the drive transistorTdr), the potential of the first gate electrode 111 is also changed,thereby encouraging the occurrence of blunt waves in the initializingsignal Sb. As a result, a delay may be caused in the operation of theinitializing transistor Tint.

In this embodiment, however, since the connecting portion 62 is formedsuch that it is not overlapped with the first gate electrode 111 or thesecond gate electrode 112, the capacitive coupling therebetween can besuppressed. Accordingly, the influence on the initializing transistorTint by a change in the potential of the connecting portion 62 isreduced, and as a result, the fast operation of the initializingtransistor Tint can be achieved.

As described above, the initializing transistor Tint and the electrodeE1 of the capacitor element C1 are electrically connected to each otherthrough the connecting portion 62. With this configuration, sufficientchannel lengths can be ensured for the selection transistor Tsl and theinitializing transistor Tint, and leakage of the current in theselection transistor Tsl or the initializing transistor Tint can besuppressed compared with the configuration with restricted channellengths. Since the selection transistor Tsl and the initializingtransistor Tint are connected to the gate electrode 521 of the drivetransistor Tdr, fluctuations in the potential of the gate electrode 521during the driving period caused by reduced leakage can be suppressed.Accordingly, in this embodiment, it is possible to maintain desiredvalues of the light quantities of the light-emitting elements E withhigh precision.

As in the element continuity portion 71 of the first embodiment, theelement continuity portion 72 shown in FIG. 15 is disposed between thedrain electrode of the drive transistor Tdr and the first electrode 21of the light-emitting element E so that it can electrically connectthem. The element continuity portion 72 is configured (substantially inan L shape) such that a part 721 extending in the Y direction iscontinuously formed with a part 722 located opposite the capacitorelement C1 across the drive transistor Tdr. The part 721 is overlappedwith a top end 171 a (see FIG. 14) of the first relay wiring pattern 171and the drain region 32 d of the semiconductor layer 32. The part 721 iselectrically connected to the top end 171 a through a contact hole Hb6passing through the first insulating layer L1.

In the area of the first insulating layer L1 that is overlapped with thedrain region 32 d, a plurality of (in this case, two) contact holes Hb7passing through the first insulating layer L1 and the gate insulatinglayer L0 are formed. The contact holes Hb7 are disposed in the Ydirection in which the gate electrode 521 is extended (i.e., along thechannel width of the drive transistor Tdr). The part 721 of the elementcontinuity portion 72 is electrically connected to the drain region 32 dthrough the contact holes Hb7.

The second relay wiring pattern 172 is extended, as shown in FIGS. 14and 15, in the Y direction such that it is overlapped with the firstrelay wiring pattern 171 and an end 452 of the semiconductor layer 45located at the negative side in the x direction. The second relay wiringpattern 172 is electrically connected to the end 452 through a contacthole Hb8 passing through the first insulating layer L1 and the gateinsulating layer L0, and is also connected to a bottom end 171 b of thefirst relay wiring pattern 171 through a contact hole Hb9 passingthrough the first insulating layer L1. In this manner, the initializingtransistor Tint and the drain region 32 d of the drive transistor Tdr(and the element continuity portion 72) are electrically connected toeach other through a relay wiring pattern 17 formed by the first relaywiring pattern 171 and the second relay wiring pattern 172.

FIG. 16 is a plan view illustrating the four unit elements P that are inthe processing step shown in FIG. 15 and disposed in the x direction andin the Y direction. The power supply line 15 of this embodiment isconfigured, as shown in FIGS. 15 and 16, such that a first portion 151extending in the x direction over a plurality of unit elements P and asecond portion 152 extending in the Y direction over a plurality of unitelements P cross each other (in a lattice-like form).

In the area of the first insulating layer L1 that is overlapped with thesource region 32 s of the semiconductor layer 32, as shown in FIG. 15, aplurality of (in this case, two) contact holes Hb10 passing through thefirst insulating layer L1 and the gate insulating layer L0 are formed.The contact holes Hb10 are disposed in the Y direction in which the gateelectrode 521 is extended. The power supply line 15 (second portion 152)is electrically connected to the source region 32 s through the contactholes Hb10.

The first portion 151 is extended in the x direction such that it passesthrough the gap between the second data line portions 132 and the gapbetween the second relay wiring pattern 172 and the element continuityportion 72 (part 721). Accordingly, when viewed perpendicularly to thesubstrate 10, as shown in FIGS. 15 and 16, the first portion 151 isoverlapped with the first data line portion 131, the first relay wiringpattern 171, and the capacitor element C1. The second portion 152 isextended in the Y direction such that it passes through the gap betweenthe element continuity portion 72 (part 722) and the second data lineportion 132 and the gap between the connecting portion 62 and the seconddata line portion 132. As shown in FIGS. 15 and 16, the power supplyline 15 is not overlapped with the selection transistor Tsl or theinitializing transistor Tint.

The entire surface of the first insulating layer L1 on which theabove-described elements are formed is covered with the secondinsulating layer L2. The light-emitting elements E and the barriers 25that partition the gaps between the light-emitting elements E areformed, as shown in FIG. 12, on the surface of the second insulatinglayer L2. As in the first embodiment, the part 722 of the elementcontinuity portion 72 is electrically connected to the first electrode21 through a contact hole Hb11 passing through the second insulatinglayer L2. The specific configurations of the light-emitting element Eand the barrier 25 are similar to those of the first embodiment.

As discussed above, in this embodiment, the element continuity portion72 is disposed opposite the capacitor element C1 across the drivetransistor Tdr. Accordingly, as in the first embodiment, the parasiticcapacitance (capacitance Cx shown in FIG. 11) formed between theelectrode E1 and the element continuity portion 72 is reduced. As aresult, the capacitance of the capacitor element C1 can be reduced.Additionally, since the power supply line 15 is formed such that it isnot overlapped with the selection transistor Tsl or the initializingtransistor Tint. Accordingly, as in the first embodiment, it is possibleto achieve a fast operation of the selection transistor Tsl and theinitializing transistor Tint with desired timings.

In this embodiment, the element continuity portion 72, the connectingportion 62, and the second relay wiring pattern 172 are formed from thesame layer as that of the power supply line 15. Also, the elementcontinuity portion 72 is disposed farther toward the negative side inthe Y direction than the drive transistor Tdr (i.e., on one side alongthe width of the power supply line 15), and the connecting portion 62and the second relay wiring pattern 172 are disposed opposite theelement continuity portion 72 (i.e., on the other side along the widthof the power supply line 15). Accordingly, a sufficient space can beformed for the first portion 151 of the power supply line 15 extendingin the x direction in the gap between the element continuity portion 72and the connecting portion 62 (second relay wiring pattern 172).Additionally, the space that is overlapped with the capacitor element C1when viewed perpendicularly to the substrate 10 can be utilized for thepower supply line 15. Thus, as in the first embodiment, the power supplyline 15 (first portion 151) can be formed to be wide so that theresistance of the power supply line 15 can be reduced.

In this embodiment, since the first portions 151 can be interconnectedto each other by the second portions 152 extending in the Y direction,the resistance of the power supply line 15 can further be reducedcompared with the configuration in which the power supply line 15 isformed of only the first portions 151. Additionally, since the firstportion 151 of the power supply line 15 is formed in a simple shape,such as a bar-like shape, a break or damage in the power supply line 15can be suppressed compared with the configuration in which the powersupply line 15 is formed in a complicated shape so that it can avoid thecomponents (element continuity portion 72 and connecting portion 62)formed from the same layer as that of the power supply line 15.

In this embodiment, in each unit element P, the data line 13 is extendedalong the periphery toward the positive side in the x direction, and therelay wiring pattern 17 is extended along the periphery toward thenegative side in the x direction. With this configuration, when focusingon one unit element P1 and a unit element P2 adjacently located towardthe negative side in the x direction, as shown in FIG. 16, the relaywiring pattern 17 of the unit element P1 intervenes between thecapacitor element C1 of the unit element P1 and the data line 13corresponding to the unit element P2. Accordingly, the capacitanceformed between the capacitor element C1 of the unit element P1 and thedata line 13 of the unit element P2 can be reduced compared with theconfiguration of the first embodiment in which the capacitor element C1of one unit element P is located in proximity with the data line 13 ofthe adjacent unit element P. With this configuration, the influence onthe capacitor element C1 of the unit element P1 by a change in thepotential of the data line 13 of the unit element P2 can be suppressed.As a result, the gate potential Vg of the drive transistor Tdr of eachunit element P and the light quantity of the light-emitting element Ecorresponding to the gate potential Vg can be set to desired values withhigh precision.

Modified Examples of Second Embodiment

A modified example of the above-described second embodiment is asfollows. FIG. 17 is a plan view illustrating the unit element P in theprocessing step shown in FIG. 14 in which the first insulating layer L1is formed. In the second embodiment, the gate electrode 521 of the drivetransistor Tdr is extended in the Y direction. In this modified example,however, as shown in FIG. 17, the gate electrode 521 of the drivetransistor Tdr is extended in the x direction. In this modified example,elements similar to those of the second embodiment are designated withlike reference numerals, and an explanation thereof is thus omitted.

The intermediate conductor 52 of this modified example includes aninterconnecting portion 525 extending from the top left of the electrodeE1 toward the negative side in the Y direction and the gate electrode521 which extends in the x direction from interconnecting portion 525and which is overlapped with the semiconductor layer 32. The gateelectrode 521 is overlapped with the entire width of the semiconductorlayer 32 in the x direction. The area of the semiconductor layer 32 thatfaces the gate electrode 521 across the gate insulating layer L0 servesas the channel region 32 c of the semiconductor layer 32. The drainregion 32 d and the source region 32 s are respectively disposed towardthe negative side and the positive side in the Y direction across thechannel region 32 c.

FIG. 18 is a plan view illustrating the unit element P in the processingstep shown in FIG. 15 in which the power supply line 15 and the elementcontinuity portion 72 are formed. The element continuity portion 72 isformed, as shown in FIG. 18, substantially in a rectangular shape in thearea opposite the capacitor element C1 across the drive transistor Tdr.As shown in FIGS. 17 and 18, the element continuity portion 72 iselectrically connected to the drain region 32 d through the plurality ofcontact holes Hb7 disposed in the x direction in which the gateelectrode 521 is extended (i.e., in the direction along the channelwidth of the drive transistor Tdr). The power supply line 15 iselectrically connected to the source region 32 s through the pluralityof contact holes Hb10 disposed in the x direction in which the gateelectrode 521 is extended.

As described above, since the gate electrode 521 of the drive transistorTdr is extended in the x direction, the drain region 32 d is formed inan elongated shape in the x direction in the area opposite the capacitorelement C1 across the gate electrode 521. With this configuration, it isnot necessary to form a portion (part 721 in the first embodiment)extending in the Y direction along the drive transistor Tdr for theelement continuity portion 72. Thus, according to this modified example,as is seen from comparison of FIG. 18 with FIG. 15, the first portion151 of the power supply line 15 extending along the gate electrode 521can be formed to be wider than that of the second embodiment.

In this modified example, the contact holes Hb7, the contact hole Hb6(the continuity portion between the relay wiring pattern 17 and theelement continuity portion 72), and the contact hole Hb1 (the continuityportion between the first data line portion 131 and the second data lineportion 132) are disposed linearly in the x direction. Accordingly, asufficient line width of the first portion 151 extending linearly (in abar-like shape) in the x direction can be ensured compared with theconfiguration in which the contact holes Hb7, Hb6 and Hb1 are displacedfrom each other in the x direction.

In the second embodiment, the gate electrode 521 is extended in thedirection orthogonal to the first portion 151 of the power supply line15. Accordingly, as the length of the gate electrode 521 (strictlyspeaking, the length of the part 721 of the element continuity portion72) becomes longer, the line width of the first portion 151 becomessmaller. In contrast, in this modified example, since the gate electrode521 is extended in parallel with the first portion 151, the length ofthe gate electrode 521 can be increased without reducing the line widthof the first portion 151. The length of the gate electrode 521corresponds to the channel width of the drive transistor Tdr.Accordingly, the channel width of the drive transistor Tdr can beincreased while maintaining the line width of the first portion 151. Itis thus possible to ensure a sufficient current to be supplied to thelight-emitting element E from the power supply line 15 via the drivetransistor Tdr having a large channel width.

Modified Examples

Various modifications can be made to the above-described embodiments.Specific modified examples are as follows. The following modifiedexamples may be combined if necessary.

First Modified Example

The electrical configuration of the unit elements P in theabove-described embodiments may be changed if necessary. Examples of thespecific mode of the unit element P that are applicable to the inventionare as follows.

A light-emission control transistor Tcnt may be inserted, as shown inFIG. 19, between the drive transistor Tdr and the light-emitting elementE. The light-emission control transistor Tcnt is a switching element forcontrolling the electrical connection between the drain electrode of thedrive transistor Tdr and the first electrode 21 of the light-emittingelement E in accordance with a light-emission control signal Sc suppliedto a light-emission control line 14. When the light-emission controltransistor Tcnt is turned ON, a current path from the power supply line15 to the light-emitting element E is formed to allow the light-emittingelement E to emit light. When the light-emission control transistor Tcntis turned OFF, the current path is disconnected to prohibit thelight-emitting element E from emitting light. With this configuration,therefore, in the period other than the initializing period and thewriting period, i.e., only in the driving period, the light-emissioncontrol transistor Tcnt is turned ON to allow the light-emitting elementE to emit light. Accordingly, the period during which the light-emittingelement E emits light can be precisely set.

In this modified example, the light-emission control transistor Tcnt isdisposed opposite the capacitor element C1 across the drive transistorTdr (i.e., toward the negative side in the Y direction). According tothis configuration, the power supply line 15 can be formed to be widersuch that it is overlapped with the drive transistor Tdr and thecapacitor element C1 compared with the configuration in which thelight-emission control transistor Tcnt is disposed in the gap betweenthe drive transistor Tdr and the capacitor element C1.

A capacitor element C2 may be inserted, as shown in FIG. 20, between thegate electrode and the source electrode (power supply line 15) of thedrive transistor Tdr. With this configuration, the gate potential Vg ofthe drive transistor Tdr set in the writing period can be held in thecapacitor element C2 during the driving period. However, if the area ofthe gate electrode (area of the channel region) of the drive transistorTdr is sufficiently large, the gate potential Vg can be held in the gatecapacitor of the drive transistor Tdr. In this case, the gate potentialVg can be held during the driving period even if the capacitor elementC2 is not disposed as in the first and second embodiments.

The unit element P shown in FIG. 21 may be also be used. In this unitelement P, the electrical connection between the gate electrode of thedrive transistor Tdr and the data line 13 is controlled by the selectiontransistor Tsl without forming the capacitor element C1 and theinitializing transistor Tint (initializing line 12). The capacitor C2 isinterposed between the gate electrode and the source electrode (powersupply line 15) of the drive transistor Tdr.

With this configuration, when the selection transistor Tsl is turned ON,the data potential Vdata corresponding to the grayscale level specifiedby the light-emitting element E is supplied to the gate electrode of thedrive transistor Tdr from the data line 13 via the selection transistorTsl. In this case, since electric charge corresponding to the datapotential Vdata is stored in the capacitor element C2, the gatepotential Vg of the drive transistor Tdr can be maintained at the datapotential Vdata even if the selection transistor Ts is turned OFF.Accordingly, the current corresponding to the gate potential Vg of thedrive transistor Tdr (i.e., the current corresponding to the datapotential Vdata) can be continuously supplied to the light-emittingelement E. Then, the light-emitting element E emits light with theluminance corresponding to the data potential Vdata.

The capacitor element C2 shown in FIG. 21 is disposed on the surface ofthe substrate 10 in a manner similar to the capacitor element C1. Inthis modified example, advantages similar to those of the first orsecond embodiment can be achieved. As described above, the capacitorelement connected to the gate electrode of the drive transistor Tdr maybe the capacitor element C1 for setting the gate potential Vg of thedrive transistor Tdr by capacitive coupling or the capacitor element C2for holding the data potential Vdata supplied to the gate electrode ofthe drive transistor Tdr from the data line 13.

Second Modified Example

In the above-described embodiments and modified examples, the firstelectrode 21 is composed of a light-reflective material. Alternatively,light emitted from the light-emitting layer 23 toward the substrate 10may be reflected by a reflective layer different from the firstelectrode 21 and may be output to the side opposite the substrate 10. Inthis configuration, a reflective layer is formed on the surface of thefirst insulating layer L1 by a light-reflective material, and the firstelectrode 21 is formed such that it covers the reflective layer. In thiscase, the first electrode 21 is composed of a light-transmissive,conductive material, such as ITO or IZO. In the above-describedembodiments, the second electrode 22 is composed of a light-transmissivematerial. Alternatively, it may be formed of a light-shielding orlight-reflective, conductive material and formed to be sufficientlythin. In this case, light emitted from the light-emitting layer 23 canpass through the second electrode 22.

The invention is also applicable to a bottom-emission-typelight-emitting device in which light emitted from the light-emittinglayer 23 passes through the substrate 10 and is output. In thisconfiguration, the second electrode 22 is composed of alight-reflective, conductive material, and also, the first electrode 21is composed of a light-transmissive, conductive material. Then, lightemitted from the light-emitting layer 23 toward the substrate 10 andlight emitted from the light-emitting layer 23 toward the side oppositethe substrate 10 and reflected on the surface of the second electrode 22pass through the first electrode 21 and the substrate 10 and are output.

Third Modified Example

In the first and second embodiments the power supply line 15 is notoverlapped with the selection transistor Tsl or the initializingtransistor Tint. However, it may be overlapped with the selectiontransistor Tsl or the initializing transistor Tint.

Fourth Modified Example

In the second embodiment, the connecting portion 62 is formed in the gapbetween the first gate electrode 111 and the second gate electrode 112of the selection transistor Tsl. Similarly, the second portion 152 ofthe power supply line 15 may be formed in the gap between the first gateelectrode 121 and the second gate electrode 122 of the initializingtransistor Tint.

Fifth Modified Example

In the first embodiment, the power supply line 15 includes only aportion extending in the x direction (corresponding to the first portion151). However, as in the second embodiment, the power supply line 15 mayalso include a portion extending in the Y direction to interconnect thefirst portions 151 (corresponding to the second portion 152). The secondportion 152 is extended in the Y direction in the gap between theconnecting portion 61 and the element continuity portion 71 shown inFIG. 7 or the gap between the adjacent unit elements P, andinterconnects the power supply lines 15 (first portions 151) locatedadjacent to each other in the Y direction. With this configuration, theresistance of the power supply line 15 can further be reduced comparedwith the first embodiment.

Sixth Modified Example

In the above-described embodiments, the light-emitting layer 23 isformed only in the inner periphery of the barrier 25. Alternatively, thelight-emitting layer 23 may be formed continuously on the entire surfaceof the substrate 10 (and more specifically, on the entire surface of thesecond insulating layer L2). With this configuration, a less expensivefilm-forming technique, such as spin coating, may be employed forforming the light-emitting layer 23. The first electrode 21 is formedfor each light-emitting element E. Accordingly, even though thelight-emitting layer 23 is continuously formed over the plurality oflight-emitting elements E, the light quantity of the light-emittinglayer 23 can be controlled for each light-emitting element E. In theconfiguration in which the light-emitting layer 23 is continuouslyformed over the plurality of light-emitting elements E, the provision ofthe barriers 25 can be omitted.

If an ink jet method (droplet discharge method) in which droplets of alight-emitting material are discharged to each space partitioned by thebarriers 25 is employed for forming the light-emitting layer 23, it ispreferable that the barriers 25 be formed on the surface of the secondinsulating layer L2, as in the first and second embodiments. The methodfor forming the light-emitting layer 23 for each light-emitting elementE can be changed according to the necessity. More specifically, alight-emitting-material film member formed on the entire surface of thesubstrate 10 may be selectively removed, or various patterningtechniques, such as a laser transfer (laser-induced thermal imaging(LTIT) method, may be employed. In this case, the light-emitting layer23 can be formed for each light-emitting element E without the need toform the barriers 25. As described above, the barriers 25 are notessential for the light-emitting device.

Seventh Modified Example

In the foregoing embodiments, the light-emitting element E includes thelight-emitting layer 23 composed of an organic EL material. However, thelight-emitting element E is not restricted to this type. For example, alight-emitting element including a light-emitting layer composed of aninorganic EL material or a light-emitting diode (LED) may be employed.That is, the specific structure or material of the light-emittingelement is not restricted as long as the light-emitting element emitslight by the supply of electric energy (typically, the supply of acurrent).

Applied Examples

Specific examples of electronic apparatuses utilizing the light-emittingdevice of an embodiment of the invention are described below. FIG. 22 isa perspective view illustrating the configuration of a mobile personalcomputer 2000 using one of the above-described light-emitting devices D.The personal computer 2000 includes one of the light-emitting devices Das a display unit and a main unit 2010. The main unit 2010 includes apower switch 2001 and a keyboard 2002. In this light-emitting device D,since the light-emitting layer 23 composed of an organic EL material isused, a screen having a wide viewing angle can be provided.

FIG. 23 illustrates the configuration of a cellular telephone 3000utilizing one of the light-emitting devices D. The cellular telephone3000 includes a plurality of operation buttons 3001, scroll buttons3002, and the light-emitting device D. The scroll buttons 3002 areoperated so that the screen displayed on the light-emitting device D canbe scrolled.

FIG. 24 illustrates the configuration of a portable information terminal4000 (personal digital assistants PDA) utilizing one of thelight-emitting devices D. The portable information terminal 4000includes a plurality of operation buttons 4001, a power switch 4002, andthe light-emitting device D as a display unit. When the power switch4002 is operated, various items of information, such as an address bookand a diary, can be displayed on the light-emitting device D.

The electronic apparatuses utilizing a light-emitting device of anembodiment of the invention may include, not only the apparatuses shownin FIGS. 22 through 24, but also digital still cameras, televisions,video cameras, car navigation systems, pagers, electronic diaries,electronic paper, calculators, word-processors, workstations,videophones, point-of-sale (POS) terminals, printers, scanners, copyingmachines, video players, and touch panels. The purpose of thelight-emitting device of an embodiment of the invention is notrestricted to the display of images. For example, in an image formingapparatus, such as a photo-writing printer or an electronic copyingmachine, a write head that exposes light to a photosensitive member inaccordance with an image to be formed on a recording material, such aspaper, is used. The light-emitting device of an embodiment of theinvention can be used as this type of write head.

1. A light-emitting device, the light emitting device comprising: alight-emitting element that is disposed above a plane of a substrate; apower supply line that is disposed above the plane of the substrate, thepower supply line having a first part which extends in a firstdirection; a first transistor that is disposed above the plane of thesubstrate, the first transistor having a first source, a first drain,and a first gate electrode, the first transistor controlling anelectrical connection between the power supply line and thelight-emitting element; a second transistor that is disposed above theplane of the substrate, the second transistor controlling an electricalconnection between the first gate electrode and one of the first sourceand first drain, the second transistor having a second source and asecond drain; and a connecting portion that electrically connects thefirst gate electrode and one of the second source and the second drain,the connecting portion that has a first side and a second side whichintersects the first side and extends in the first direction, the lengthof the second side being longer than the length of the first side. 2.The light-emitting device according to claim 1, the power supply linefurther having a second part which extends in a second directionintersecting the first direction.
 3. The light-emitting device as setforth in claim 1, further comprising: an electrical continuity portionthat electrically connects one of the first source and the first drainand the light-emitting element, the electrical continuity portion thathaving a third side and the forth side that extends in the firstdirection, and the length of the forth side being longer than the lengthof the third side.
 4. The light-emitting device as set forth in claim 1,in a first period, a current being supplied from the power supply lineto the light-emitting element, and in a second period before the firstperiod, one of the first source and the first drain being electricallyconnected to the first gate electrode through the second transistor. 5.The light-emitting device as set forth in claim 1, the light-emittingelement having a first pixel electrode, a second pixel electrode, alight emitting layer disposed between the first pixel electrode and thesecond pixel electrode, and the first pixel electrode having a portionoverlapping the power supply line when viewed from a third directionperpendicular to the plane of the substrate.
 6. The light-emittingdevice as set forth in claim 1, the connecting portion being formed in afirst layer in which the power source line is formed.
 7. Thelight-emitting device as set forth in claim 1, further comprising: adata line, the data line extending in the first direction.
 8. Anelectronic apparatus, comprising: the light-emitting device as set forthin claim
 1. 9. A light-emitting device disposed above a substrate, thelight emitting device comprising: a data line that is disposed above aplane of a substrate and extends in a first direction; a light-emittingelement that is disposed above the plane of a substrate; a power supplyline that is disposed above the plane of a substrate; a first transistorthat is disposed above the plane of a substrate, the first transistorcontrolling an electrical connection between the power supply line andthe light-emitting element, the first transistor having a first source,a first drain, and a first gate electrode; a second transistor that isdisposed above the plane of a substrate, the second transistorcontrolling an electrical connection between the first gate electrodeand one of the first source and the second drain, the second transistorhaving a second source and a second drain; and a connecting portion thatelectrically connects the first gate electrode and one of the secondsource and the second drain, the connecting portion having a first sideand a second side which intersects the first side and extends in thefirst direction, the length of the second side being longer than thelength of the first side.
 10. A light-emitting device, the lightemitting device comprising: a light-emitting element that is disposedabove a plane of a substrate; a power supply line that is disposed abovethe plane of a substrate, the power supply line extending in a firstdirection; a first transistor that controls an electrical connectionbetween the power supply line and the light-emitting element; and anelectrically continuity portion that electrically connects the firsttransistor and the power supply line, the electrically continuityportion having a third side and a forth side which intersects the thirdside and extends in the first direction, the length of the third sidebeing longer than the length of the forth side.